Neuron transplant to treat Parkinson’s disease

Parkinson's disease treatment mainly relies on therapies to counteract the dopamine deficiency in patients, with the possible use of deep brain stimulation in some cases. A new therapeutic strategy is currently being tested: the transplantation of dopaminergic neurons.

Parkinson’s disease is the second most common 𝐧𝐞𝐮𝐫𝐨𝐝𝐞𝐠𝐞𝐧𝐞𝐫𝐚𝐭𝐢𝐯𝐞 𝐝𝐢𝐬𝐞𝐚𝐬𝐞 in France and mainly affects the elderly, peaking between the ages of 85 and 89. The disease is caused by 𝐝𝐨𝐩𝐚𝐦𝐢𝐧𝐞𝐫𝐠𝐢𝐜 𝐧𝐞𝐮𝐫𝐨𝐧 𝐝𝐞𝐠𝐞𝐧𝐞𝐫𝐚𝐭𝐢𝐨𝐧. Although the vast majority of cases are sporadic, a genetic origin can be found in some cases (around 5%). Symptoms appear when the loss of dopaminergic neurons is such that the brain 𝐜𝐚𝐧 𝐧𝐨 𝐥𝐨𝐧𝐠𝐞𝐫 𝐜𝐨𝐦𝐩𝐞𝐧𝐬𝐚𝐭𝐞 (50% to 70% of neurons destroyed).

Japanese and US teams have tested a 𝐧𝐞𝐰 𝐭𝐡𝐞𝐫𝐚𝐩𝐞𝐮𝐭𝐢𝐜 𝐚𝐩𝐩𝐫𝐨𝐚𝐜𝐡. Indeed, they have just published in 𝑁𝑎𝑡𝑢𝑟𝑒 the results of transplanting 𝐭𝐰𝐨 𝐭𝐲𝐩𝐞𝐬 𝐨𝐟 𝐬𝐭𝐞𝐦 𝐜𝐞𝐥𝐥𝐬 capable of becoming new dopaminergic neurons into seven and 12 patients, respectively. The neurons were transplanted into the 𝐩𝐮𝐭𝐚𝐦𝐞𝐧. No significant adverse effects were reported in either study. Although these studies were designed to assess the feasibility and safety of the procedure, the US study showed that the graft remained active for 𝐚𝐭 𝐥𝐞𝐚𝐬𝐭 𝟏𝟖 𝐦𝐨𝐧𝐭𝐡𝐬, with a 50% 𝐫𝐞𝐝𝐮𝐜𝐭𝐢𝐨𝐧 in symptoms. The Japanese results were also very encouraging.

The next step is a Phase III study involving more patients. This is a very 𝐞𝐧𝐜𝐨𝐮𝐫𝐚𝐠𝐢𝐧𝐠 𝐩𝐫𝐨𝐬𝐩𝐞𝐜𝐭, as treatments to counter dopamine deficiency become less and less effective over time.